Method for increasing bit load

ABSTRACT

A circulation system in which a drilling fluid flows from the surface, through a pipe, through a motor and a drill bit, and returns to the surface through the annular area between the outside diameter of the pipe and the internal diameter of the hole being drilled, to urge the drilling system forward by providing a seal which engages the internal diameter of the hole being drilled, providing a booster pump to pump the drilling fluids between the seal and the outer diameter of the drilling system such that the pressure downstream of the booster pump is higher than the pressure upstream of the booster pump by a differential pressure giving a force generally proportionate to the area within the diameter of the sealing engagement with the internal diameter of the bore times the differential pressure to urge the drilling system forward.

CROSS-REFERENCE TO RELATED APPLICATIONS

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STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK

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BACKGROUND OF THE INVENTION

The field of this invention of that of moving pipe into a generally horizontal hole and drilling at the end of the hole. The distance at which the pipe can be pushed into a generally horizontal hole is limited by the forces available and the column buckling characteristics of the pipe.

Pipes are used to push in horizontal directions for activities such as drilling in oil and gas wells as holes are drilled horizontally thru shallow but wide pockets or reservoirs of oil or gas. Once the wells are drilled, cleanout or secondary production operations can be enhanced by a smaller string of tubing being inserted into the horizontal runs. The use of the smaller but faster strings has been limited due to the limited load which can be put on a bit at the end of the tubing.

A variety of other pipes exist in which improved “bit load” can be useful includes sewage systems, water lines, and pipelines.

Especially in the case of thin wall pipe such as coiled tubing which can be unreeled into a pipe, column buckling strength is low. As the pipe is not actually assured of being straight in the first place, column buckling resulting in a spiral configuration in the well will cause high friction with the wall of the hole. This friction will limit and/or stop forward movement of the pipe, and eliminate or limit the available end loading available to a drilling bit at the end of the tubing.

When the generally horizontal hole begins with a vertical hole such as in an oil or gas well, the transmission of force around the curve between vertical and horizontal further limits the forces available in the generally horizontal section.

BRIEF SUMMARY OF THE INVENTION

The object of this invention is to provide a method which will provide a forward motive force for tools and pipes which are in generally horizontal holes.

A second object of the present invention is to provide a motive force which will increase the load on a drill bit while the drill bit is drilling.

A third object of the present invention is to provide a method of providing lower pressures at the drilling bit to enhance drilling penetration rate.

A fourth object of the present invention is to provide means to move the jetting head of a pipeline blockage remediation system forward while pumping into the internal string of pipe and taking returns up the larger annulus rather than pumping down the annulus and having to take the returns back up the smaller internal diameter of the internal string.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

Figure no. 1 is a section of the earth showing a well being drilled with the system of this invention being in place.

Figure no. 2 is a closer view of a portion of FIG. 1 showing the general area of the drilling system without the benefits of the present invention for comparison.

Figure no. 3 is a closer view of a portion of FIG. 1 showing the general area of the drilling system with the benefits of the present invention for comparison.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a drilling system 1 in a well bore 3. The drilling system generally comprises a drill bit 5, a booster pump 7, a sealing cup 9, and a drill motor 12. A drilling and circulating string 14 is used to push the drilling system along well bore 3 and provide hydraulic power for drill motor 12. Drilling system will often also include directional control systems 16 which require control cables 18.

A relatively vertical casing 20 is shown with a whipstock device 22 shown to divert the drilling operations from vertical to more horizontal as is well known in the art. The figure illustrates that a window 24 has been milled in the side of the casing 20 off whipstock 22 to start the diversion of the string from near vertical to near to horizontal, or in some cases fully horizontal. For clarity on the drawing the turn to horizontal is shown to be almost within the size of the casing, whereas in reality the turn to horizontal can take hundreds of feet.

Numerous flow arrows 26 shown that the fluids flow down from the surface 28 thru the internal diameter of the smaller string 14, thru the drilling system, and back up the annular area within the internal hole of the bore being drilled to the surface 28.

Referring now to FIG. 2, drilling system is shown 1 in a well bore 3 which does not have the means of the present invention. The figure shows the drill bit 5, a mud motor 12, drilling and circulating string 14, and flow arrows 26.

For purpose of discussion of this figure we will presume that the operations are occurring at a depth of about 1000 feet, such that the ambient or non-flowing pressure is 1,000 p.s.i. at locations P1, P2, P3, and P4. This would reflect that the pressure gradient of the drilling fluid system to be about ½ p.s.i. per foot which is a relatively light weight drilling fluid.

When a sample flow is started, the annulus pressure P1 still approximates 1000 p.s.i. P2 is also 1000 p.s.i. as it is the same space and there is minimal flow loss up the large annulus area. The reason for identifying the pressure in these two similar places will be understood in figure no. 3. P3 is inside the bit and reflects the flow loss across the jet nozzles 30, increasing to 1300 p.s.i. or a 300 p.s.i. differential. Pressure P4 is 1400 p.s.i. or a 100 p.s.i. differential to hydraulically provide the power to drive the motor to turn the bit.

Referring now to figure no. 3, drilling system has a booster pump 7 in the annulus above the drilling bit 5 and a flexible cup seal 9 to seal on the formation hole or I.D. of the pipe the unit is passing thru. Booster pump 7 is shown with bearing and seal sets 40 and 42, rotating turbine blades 44, stationary turbine blades 46, lower centralizer ring 48, upper centralizer ring 50, upper connection 52, and hoses 54. Lower and upper centralizer rings 48 and 50 keep the sealing cup 9 generally centralized so that it will remain in sealing contact with the well bore 3. Upper connection 52 prevents the sealing cup 9 from being turned backward and inside out when the system is pulled out of the hole.

The rotating blades 44 of the turbine type booster pump is spun on the same shaft as the drilling bit 5 and in combination with the stationary blades 46, it produces a pumping differential, in this sample case about 20 p.s.i. P1 remains at 1,000 p.s.i., but P2 is reduced to 980 p.s.i. Inside the drill bit 5 with the same 300 p.s.i. differential across the jets 30 the pressure is reduced to 1,280 p.s.i. The motor is taking an extra 100 p.s.i. to power the rotating blades 32, so the pressure is increased by 100 p.s.i. but reduced by the 20 p.s.i. from the booster pump 7, giving a net pressure of 1480 p.s.i.

The 980 p.s.i. at P2 above the bit is a relative vacuum in comparison to the expected 1000 p.s.i., so in a sense, the system works by vacuuming the bit towards the end of the hole.

If we presume we are drilling a 6⅝″ diameter hole, the seal engagement between the bore and the cup seal provides an area of the 34.471 sq. in. The 20 p.s.i. differential from the booster pump across this area yields a force on the bit of 34.471*20=689.4 lbs.

This is 689.4 lbs of bit force for drilling at a location where otherwise zero force might be available.

The example given is a nominal set of values which will be achieved as desired. As larger bores are encountered, less of a pressure differential will be desired to prevent overloading the bits. A 20 p.s.i. differential in a 20″ bore will provide a 10,000 lb. load on the bit. In smaller bores, a longer impeller will be desired to provide higher differentials for loading.

It is understood in the art that reducing the head pressure on the formation at the point of drilling will often speed the drilling rate. This is called underbalanced drilling. Complex systems of percolating some nitrogen in the annulus of drilling wells is sometimes used to implement this principle. This system literally reduces the head pressure specifically on the drilling area by 20 p.s.i. in this case. When properly balanced, it will allow an overbalance in the bore of the hole away from the drill bit and an under balance in the area of the bit to optimize drilling.

Remediation of a blockage in a pipeline requires that access to the blockage is achieved with a small circulating string of pipe within the pipeline, usually coiled tubing. Pushing a string of coiled tubing into a horizontal pipeline is typically hindered by the difficulty in pushing coiled for significant distances. Pushing coiled tubing is generally limited to about one mile before the coiled tubing buckles into a helical pattern and friction locks in the pipeline. One solution is to place a sealing cup on the end of the pipeline and pressuring the backside of the cup. This has the limitation of the returns having to come back the smaller bore of the I.D. of the coiled tubing.

The present invention offers the advantage of the high pressure pumping down the I.D. of the coiled tubing and the return back up the much larger annulus area. It can also offer higher pressures to power the drill motor to provide the motive force for the end of the coiled tubing of a relative vacuum.

The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below. 

1. In a circulation system in a hole in which a fluid flows from a starting location, through a pipe within said hole, through a motor, and returns to said starting location through the annular area between the outside diameter of said pipe and the internal diameter of said hole, the method of urging said motor further from said starting location, comprising providing a seal which sealingly engages said internal diameter of said hole, providing a booster pump to pump said fluids between said seal and the outer diameter of said pipe such that the pressure downstream of said booster pump is higher than the pressure upstream of said booster pump by a differential pressure, such that a force generally proportionate to the area within the diameter of said sealing engagement with said internal diameter of said hole times said differential pressure urges said motor forward.
 2. The invention of claim 1, wherein fluid leaving the distal end of said pipe removes material from the end of said hole and increases the length of said hole from said starting location.
 3. The invention of claim 1, wherein said motor rotates a drilling bit which removes material from the end of said hole and increases the length of said hole from said starting location.
 4. The invention of claim 3, wherein urging said motor further from said starting location increases load on said drilling bit at the distal end of said hole from said starting location.
 5. The invention of claim 1, wherein said motor is urged forward in a generally horizontal direction.
 6. The invention of claim 1, wherein said seal is a pressure energized cup type seal.
 7. The invention of claim 5, wherein said pressure energized cup type seal has a connection to said motor which keeps said energized cup type seal from being turned inside out during retrieval from the hole.
 8. The invention of claim 1, wherein booster pump is a turbine style pump.
 9. The invention of claim 8, wherein the rotating section of said turbine type booster pump is rotated by said motor.
 10. In a circulation system in which a drilling fluid flows from the surface, through a pipe, through a drilling system comprising a motor and a drill bit, and returns to said surface through the annular area between the outside diameter of said pipe and the internal diameter of the hole being drilled, the method of urging said drilling system forward, comprising providing a seal which sealingly engages said internal diameter of said hole being drilled at a location between said drilling bit and said surface, providing a booster pump to pump said drilling fluids between said seal and the outer diameter of said drilling system such that the pressure downstream of said booster pump is higher than the pressure upstream of said booster pump by a differential pressure, such that a force generally proportionate to the area within the diameter of said sealing engagement with said internal diameter of said bore times said differential pressure urges said drilling system forward.
 11. The invention of claim 10, wherein urging said drilling system forward increases the load on the area to be drilled.
 12. The invention of claim 11, wherein the area to be drilled is formations within the earth.
 13. The invention of claim 10, wherein said drilling system is urged forward in a generally horizontal direction.
 14. The invention of claim 10, wherein said seal is a pressure energized cup type seal.
 15. The invention of claim 14, wherein said pressure energized cup type seal has a connection to said drilling system on the end distal from said bit which keeps said energized cup type seal from being turned inside out during retrieval from the hole.
 16. The invention of claim 10, wherein booster pump is a turbine style pump.
 17. The invention of claim 16, wherein the rotating section of said turbine type booster pump is rotated by said motor.
 18. In a circulation system in which a drilling fluid flows from the surface, through a pipe, through a drilling system comprising a motor and a drill bit, and returns to said surface through the annular area between the outside diameter of said pipe and the internal diameter of said hole being drilled, the method of increasing the load on said drilling bit on the formations to be drilled to improve the drilling operations, comprising providing a seal which sealingly engages said internal diameter of said hole being drilled at a location between said drilling bit and said surface, providing a booster pump to pump said drilling fluids between said seal and the outer diameter of said drilling system such that the pressure downstream of said booster pump is higher than the pressure upstream of said booster pump by a differential pressure, such that a force generally proportionate to the area within the diameter of said sealing engagement with said internal diameter of said bore times said differential pressure urges said drilling system forward.
 19. The invention of claim 18, wherein said load is increased on said drill bit by urging said drilling system forward. 